AntoineAsphalt.caRiver Rock or Mulch: Which Should I Use?
Quick answer
Use mulch in planting beds where you want the soil to improve, because organic mulch breaks down and feeds soil life. Use river rock where you want a surface that doesn't decompose, knowing it costs more up front: about US$60 to US$170 per ton for the material (typical market range, Lawn Love, October 5, 2026). Both are usually spread 2 to 3 inches deep.
What's the difference between river rock and mulch?
| River rock | Organic mulch | |
|---|---|---|
| Breaks down? | No | Yes |
| Feeds the soil? | No | Yes, as it breaks down |
| Typical depth | 2–3 inches | 2–3 inches |
| Up-front cost | Higher | Lower |
| Upkeep | Described as low-maintenance | Needs topping up as it breaks down |
Toronto Master Gardeners note that leaves and other organic mulch break down and feed soil life.
How much does river rock cost?
We found no Canadian price source. US figures, typical market range (Lawn Love, US dollars, October 5, 2026):
| Item | Range |
|---|---|
| Material, per ton | $60–$170 |
| Material, per cubic yard | $45–$140 |
| Installed, 250–800 sq ft | $145–$2,375 (most pay $365–$1,500; average $655) |
| Labour | $40–$90 an hour, about 2 hours per ton placed |
For mulch prices, see our guide on how much mulch you need.
How much river rock do I need?
Lawn Love says:
- 1 cubic yard of river rock weighs about 1.4 tons.
- About 1.3 tons covers 100 sq ft at 3 inches deep.
To work it out: tons = square feet × depth in inches ÷ 324 × 1.4.
Where does river rock make more sense than mulch?
Rock doesn't break down, so it suits spots where you want a surface that stays put and you aren't trying to feed the soil, such as along a foundation or around a downspout. In beds full of perennials, shrubs and vegetables, mulch adds organic matter as it breaks down.
Do I need landscape fabric under river rock?
Fabric is often laid under rock, but Toronto Master Gardeners say they don't recommend landscape fabric.
River rock calculator
- Cubic yards
- 0.00 yd³
- Tons
- 0.0 t
- Round up when ordering
- 0.0 t
Lawn Love: about 1.3 tons covers 100 sq ft at 3 inches.
Formulas: cubic yards = sq ft × depth ÷ 324; tons = cubic yards × 1.4.
Rock density varies by stone and size. Confirm with your supplier.
Frequently asked questions
How deep should river rock be?
Lawn Love recommends 2 to 3 inches.
How many tons are in a cubic yard of river rock?
About 1.4 tons, according to Lawn Love.
Should I use landscape fabric under rock?
Toronto Master Gardeners don't recommend landscape fabric.
Is river rock cheaper than mulch over time?
We found no Canadian comparison. Rock costs more up front and doesn't break down. Mulch costs less but needs topping up as it breaks down.
Related guides & services
Compare our rock installation and mulch installation services.
Prices are US typical market ranges in US dollars, not Antoine's prices.
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